'97 Malibu electrical issue

I Have a 1997 Malibu in which the battery drains for no apparent reason. The battery is new, and the alternator is goog (just had it checked). Several months ago I had the ignition switch assembly changed. The batter drain problem just started this past week. Any ideas???

off the top of my head, i would have to say that it probably is the alternator
not charging the battery fully. You may want to take the cables off the battery and see if they are corroded, neg first then pos, put back pos first, neg last. Does the battery have a " sight" is it green , light or dark, of course that is only one cell that it sees. use baking soda mixed in water to clean the terminals. be carefull when removing the cable, especially the pos, if the end of the wrench hits metal while the other end is on the pos , you could short the battery. If there is still a warranty on the battery , i would do nothing and take the car and the battery back.

All of what you stated had already been done, still no luck!!!

Depending how fast it discharges,..if it's over night. I've seen alternators check out great, but not "shut off" when you turn the key off. Try unhooking the positive post off the alternator and see if it still discharges after. If it does, the internal voltage regulator is staying on. There are two ways to fix it. One, replace the alt. Or find a shop like I have in my town that car rebuild them at half the cost and still use GM parts.
If the battery is still discharging, it sounds like something is staying like a trunk light or something to that nature.
I've also seen batterys get shorted out inside and discharge themselves.
Hope that gives you some ideas, good-luck

Just replaced the fusable link on the starter due to being burnt. Got car starter and link got very hot in a short period of time. Could it possible be something with the ignition system?